My present invention relates to a container composed of synthetic resin material and, especially, a box-shaped container having a bottom which is formed on its exterior with a riding rim and with stiffening ribs.
Box-like containers, especially for storage and transport of solids and liquids, can be comprised of synthetic resin materials and are available in a variety of configurations and constructions. The box or parts thereof may be fabricated by injection-molding techniques and, for example in German patent document DE 37 09 190 C2, a container is described which is formed on the underside of its bottom with stiffening ribs. The stiffening ribs contribute strength to the bottom, which otherwise may be thin-walled, to prevent bulging or deformation of the body under loads such as the load of the material within the container.
In this latter container, the bottom is formed with a running rim or riding rim by means of which the bottom of the container can be displaced onto and can ride along the roller conveyors or the like. The ribs formed on the bottom may provide openings into which a fork can be inserted, enabling the container to be handled with a fork lift vehicle.
In the past, the load within the container often deformed the bottom so that travel of the container onto a conveyor or other surface was prevented or inhibited. In addition with higher loads, the bottom was frequently deformed.
More specifically, when ribs have been provided on the bottom of a container, the travel of the container on and onto rollers and ball conveyor surfaces has been difficult to achieve. The use of automatic equipment for transferring the containers to support and conveyor surfaces has also been precluded.
It is, therefore, the principal object of the present invention to provide an improved box-like container which can more easily be transferred from one surface to another and displaced along or onto a conveyor than has been the case heretofore.
Another object of this invention is to provide a container for bulk material which can be loaded to a greater extent than has hitherto been the case and nevertheless will not impede transfer of the container onto or along a conveyor.
Still another object of this invention is to provide a container of the type described at the outset which not only has a bottom with a high degree of stiffness but which also will not catch on surface formations of conveyors or supporting surfaces for the container and thus can easily be slid along such surfaces.
A further object of this invention is to provide a bulk container with a high degree of slideability and bottom stiffness and yet which can be fabricated by injection-molding techniques and thus can be manufactured simply and economically.
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a box-like container having a bottom formed with outwardly extending ribs capable of stiffening the bottom and running substantially toward edges of the bottom and flaps connected by film hinges or like means to the bottom and swingable to cover the ribs at least along a sliding rim of the bottom, thereby providing smooth surfaces for the riding rim which enable the container to be transferred to and from conveyors and conveyor surfaces.
According to the invention, the underside of the bottom has film hinges or like ligatures elastically connecting the flaps to the bottom and enabling them to cover at least some of the ribs in the region of the rim and to form smooth surfaces of the rim upon which the container is supported. The flaps may be injection molded in one piece with the bottom and with the film hinge and thus can be integrated in and in one piece with the container. The flaps can form a peripherally closed frame-like riding rim with a smooth surface by which the container can be transported along ball surfaces or roller conveyors since the conveyor balls or wheels or rollers can no longer catch in the ribs or the spaces between them. The ribs also cannot engage between the balls or between the rollers of the conveyor surfaces and that ensures that the container, on a roller table or ball table can readily change directions and be shifted in practically any direction.
The attachment of the cover strips to the bottom of the container, e.g. to a wall structure forming the body of the container and integral with the bottom, can be via a film hinge or, as will be apparent by two or more film hinges or some other bendable, elastic and flexible member forming the connecting ligature. The ligatures allow the inward (or outward) swinging of the strip to cover the ribs, i.e. to underlie the ribs and form the sliding rim which enables the container to be moved without catching on the ribs.
The film hinges or other ligatures can be injection molded together with the container body and the bottom. The sliding rim is thus formed in one piece with the rest of the container.
Preferably, once the strips are folded inwardly they can be attached to the bottom of the container, preferably to the reinforcing ribs, by welding. To retain the strips in their inwardly folded positions, they may be provided with catches which can engage the ribs of the bottom.
The fact that the strips themselves are part of the container body or bottom and can be manufactured directly with the remainder of the container, e.g. by injection molding, but nevertheless can be fabricated in any orientation, being bent into position only during a final procedure after the molding has been completed, enables the container structure to be removed from the mold with ease.
After the demolding step, the strips need only be swung inwardly or bent inwardly and retained in place by welding or the aforementioned catches. The system of the invention results in a substantially cost-saving fabrication, because additional expense for the sliding rim elements can be avoided. The securing of the strip elements to the stiffening ribs, especially by welding, can ensure the formation of hygienically sealed structures with a smooth underside and which can easily be cleaned. The bottom can withstand substantial loads since the rib structure can utilize any number of dimensions of ribs and a greatly increased number of longitudinal and/or transverse and/or diagonal ribs in any pattern, independently of the sliding rim structure. A honeycomb or diamond configuration can be provided. The sliding rim itself is an extremely strong sandwich-like structure because it consists of inner and outer flanges with a rib structure between them and which is exceptionally resistant to torsion as well as to compressive loading. By variation in the degree to which the strips underlie the rib structure of the bottom, the strength of the bottom can be varied in creation of such a sandwich structure. In fact, in the extreme case, the ribs from opposite sides of the container can practically meet so that the rib structure is fully covered at the underside by the strips.
When the container body is a double-wall structure, the strips themselves may be formed in two parts with one part being connected by a respective film hinge or other ligature to an outer wall element of the double-wall structure while the first part is connected to the second part, which actually underlies the rib structure, by another film hinge or ligature. The film hinges may extend continuously the full lengths of the strips or strip parts or may be provided in separate or spaced apart segments along the length of the strip or part thereof.
The strips can easily be formed in horizontal positions parallel to the bottom in the mold and, upon demolding can then be bent at the two ligatures so that the second part of the strip underlies the rib structure of the bottom. The first part thus serves to bridge the spacing between the outer wall of the container body and the rib structure on the bottom while the second part serves to underlie the rib structure.
A further feature of the invention, also applicable to a double-wall container body, has the outer wall connected by one ligature or film hinge to the strip and the strip formed with an angle section at its side connected to the film hinge or ligature so as to allow the orientation of the strip connected to the angle section to cover the ribs while the angle section bridges the gap between the outer wall and the rib structure. In this case, between the outer wall and the rib structure, a recess is provided in which the angle structure can be received.
The angle structure can be formed in one piece with the rib-covering part of the strip. In the injection molding of the container, the strip itself can have a vertical orientation so that the closing force of the molding die can be reduced.
The strip can be provided at its free edges remote from the hinge axis with a detent or locking member which can be injection molded on the strip. This member can be a pin or lug with a nose-like end engageable in a recess or behind a shoulder of a respective stiffening rib. In that case, the strip need only be swung upwardly about the axis of the injection-molded film hinge to be clipped to the rib structure.
According to a further feature of the invention the film hinge is provided on the side of the strip turned toward the outer wall of the container. In that case, the strips are swung inwardly over the ribs in the rim region and can be locked to one or more of the stiffening ribs by the detent means. Between this film hinge and the outer wall of the container, a bridge piece can be provided on the container wall or on the film hinge. Alternatively, the film hinge can be provided along the edge of the strip which is turned away from the outer wall of the container and the film hinge can thus be when one of the stiffening ribs and the strip can be swung outwardly to cover the ribs in the rim region. In that case, the detent means can lock the strips in place proximal to an outer edge of the container bottom.
According to still another feature, the entire rib structure on the underside of the bottom can be covered by a cover plate formed in one or more pieces and which can be retained against the rib structure by welding or by detent means as previously described. The cover can be connected to the bottom by a film hinge or other longitudinal structure.
The assembly formed by the bottom wall, the rib structure and the cover plate constitutes a sandwich structure which has particularly high strength. Since a smooth surface can be formed over the entire bottom, the container can travel more readily over surfaces. The bending resistance of the bottom is enhanced. In this case as well as in the case in which the strips form the rim, the film hinge or ligature can be injection molded together with the bottom and the plate along a transverse or longitudinal wall of the container.
When a cover plate is provided, it can be held in its middle region as well as along edges opposite the ligature to the ribs on the underside of the bottom. The detent means which is used for that purpose can be snap hooks, clops, barbed hooks or the like which can be formed on the rib structure or the container bottom or on the cover plate or strip and can be engageable in a hole or opening in the opposing member. More particularly, the box shaped container of the invention can comprise:
a bottom formed of a synthetic resin material and having downwardly projecting stiffening ribs, and strips connected to the bottom by bendable ligatures and adapted to cover the ribs at least along part of a perimeter of the bottom, thereby forming a riding rim along the bottom.
Alternatively the box shaped container can comprise:
a bottom formed of a synthetic resin material, and a double-wall structure on the bottom, the bottom having downwardly projecting stiffening ribs, and a cover plate formed in at least one piece and connected to the bottom by at least one bendable ligature and adapted to cover the ribs, thereby forming a riding surface along the bottom.